Fixed warnings in gcc 7

dlib/general_hash/murmur_hash3.h

@@ -214,7 +214,9 @@ namespace dlib
         switch(len & 3)
         {
             case 3: k1 ^= tail[2] << 16;
+                    // fall through
             case 2: k1 ^= tail[1] << 8;
+                    // fall through
             case 1: k1 ^= tail[0];
                     k1 *= c1; k1 = DLIB_ROTL32(k1,15); k1 *= c2; h1 ^= k1;
         };
@@ -384,24 +386,24 @@ namespace dlib
 
         switch(len & 15)
         {
-            case 15: k2 ^= uint64(tail[14]) << 48;
-            case 14: k2 ^= uint64(tail[13]) << 40;
-            case 13: k2 ^= uint64(tail[12]) << 32;
-            case 12: k2 ^= uint64(tail[11]) << 24;
-            case 11: k2 ^= uint64(tail[10]) << 16;
-            case 10: k2 ^= uint64(tail[ 9]) << 8;
+            case 15: k2 ^= uint64(tail[14]) << 48; // fall through
+            case 14: k2 ^= uint64(tail[13]) << 40; // fall through
+            case 13: k2 ^= uint64(tail[12]) << 32; // fall through
+            case 12: k2 ^= uint64(tail[11]) << 24; // fall through
+            case 11: k2 ^= uint64(tail[10]) << 16; // fall through
+            case 10: k2 ^= uint64(tail[ 9]) << 8; // fall through
             case  9: k2 ^= uint64(tail[ 8]) << 0;
-                     k2 *= c2; k2  = DLIB_ROTL64(k2,33); k2 *= c1; h2 ^= k2;
-
-            case  8: k1 ^= uint64(tail[ 7]) << 56;
-            case  7: k1 ^= uint64(tail[ 6]) << 48;
-            case  6: k1 ^= uint64(tail[ 5]) << 40;
-            case  5: k1 ^= uint64(tail[ 4]) << 32;
-            case  4: k1 ^= uint64(tail[ 3]) << 24;
-            case  3: k1 ^= uint64(tail[ 2]) << 16;
-            case  2: k1 ^= uint64(tail[ 1]) << 8;
+                     k2 *= c2; k2  = DLIB_ROTL64(k2,33); k2 *= c1; h2 ^= k2; // fall through
+
+            case  8: k1 ^= uint64(tail[ 7]) << 56; // fall through
+            case  7: k1 ^= uint64(tail[ 6]) << 48; // fall through
+            case  6: k1 ^= uint64(tail[ 5]) << 40; // fall through
+            case  5: k1 ^= uint64(tail[ 4]) << 32; // fall through
+            case  4: k1 ^= uint64(tail[ 3]) << 24; // fall through
+            case  3: k1 ^= uint64(tail[ 2]) << 16; // fall through
+            case  2: k1 ^= uint64(tail[ 1]) << 8; // fall through
             case  1: k1 ^= uint64(tail[ 0]) << 0;
-                     k1 *= c1; k1  = DLIB_ROTL64(k1,31); k1 *= c2; h1 ^= k1;
+                     k1 *= c1; k1  = DLIB_ROTL64(k1,31); k1 *= c2; h1 ^= k1; // fall through
         };
 
         //----------

dlib/serialize.h

@@ -277,7 +277,7 @@ namespace dlib
             size &= 0x0F;
             
             // check if the serialized object is too big
-            if (size > sizeof(T))
+            if (size > (unsigned long)tmin<sizeof(T),8>::value || size == 0)
             {
                 return true;
             }
@@ -391,7 +391,7 @@ namespace dlib
             size &= 0x8F;
 
             // check if an error occurred 
-            if (size > sizeof(T)) 
+            if (size > (unsigned long)tmin<sizeof(T),8>::value || size == 0)
                 return true;
            
 

dlib/svm/pegasos.h

@@ -355,7 +355,7 @@ namespace dlib
             //typedef typename K::sample_type sample_type;
             typedef typename K::mem_manager_type mem_manager_type;
 
-            caching_kernel () : samples(0), counter(0), counter_threshold(0) {}
+            caching_kernel () {}
 
             caching_kernel (
                 const K& kern,
@@ -458,12 +458,12 @@ namespace dlib
                 std::vector<std::pair<long,long> > frequency_of_use;  
             };
 
-            const sample_vector_type* samples;
+            const sample_vector_type* samples = 0;
 
             std::shared_ptr<cache_type> cache;
-            mutable unsigned long counter;
-            unsigned long counter_threshold;
-            long cache_size;
+            mutable unsigned long counter = 0;
+            unsigned long counter_threshold = 0;
+            long cache_size = 0;
         };
 
     // ------------------------------------------------------------------------------------

dlib/svm/svm_c_linear_trainer.h

@@ -692,7 +692,7 @@ namespace dlib
         bool learn_nonnegative_weights;
         bool last_weight_1;
         matrix<scalar_type,0,1> prior;
-        scalar_type prior_b;
+        scalar_type prior_b = 0;
     }; 
 
 // ----------------------------------------------------------------------------------------

dlib/test/cca.cpp

@@ -375,6 +375,7 @@ namespace
 
 // ----------------------------------------------------------------------------------------
 
+    /*
     typedef std::vector<std::pair<unsigned int, float>> sv;
     sv rand_sparse_vector()
     {
@@ -423,6 +424,7 @@ namespace
 
         timing::print();
     }
+    */
 
 // ----------------------------------------------------------------------------------------
 

dlib/xml_parser/xml_parser_kernel_1.h

@@ -357,6 +357,7 @@ namespace dlib
 
 
                 case empty_element: is_empty = true;
+                                    // fall through
                 case element_start:
                     {
                         seen_root_tag = true;